The present invention relates generally to industrial bags, and more particularly, the present invention relates to an easy open industrial bag.
Industrial bags, often made from multi-ply kraft paper, synthetic sheets, and combinations thereof, are closed in numerous ways. A common closure is referred to as a pinch bottom where a flap of one wall of the bag is folded over and glued or otherwise secured to another wall of the bag. The pinch bottom closure is commonly used in gusseted bags and flat tube bags.
Once closed it becomes necessary at some point to open the bag. In bags that were sewn shut, it is possible to open the bag by undoing the stitching. Sewing generally requires substantial additional processing equipment and processing expense, and thus is no longer a preferred closure method. Providing a glued closure for a pinch bottom bag provides for an easily automated process that is inexpensive and yields a secure sift resistant closure. However, glued closures are difficult to open without cutting the bag, or substantially tearing the walls of the bag. The walls of the bag, of course, are designed to resist tearing, which further makes opening of the bag difficult, and cutting requires having a cutting tool to be handy.
In U.S. Pat. No. 4,480,752 there is disclosed a feature for a pinch bottom bag that facilitates the opening of the bag. The feature includes a tab which is bonded inside the bag within one of the side wall gusset folds. A portion of the tab extends out of the interior of the bag and as the bag is folded closed, remains exposed to the exterior of the bag. By pulling on the tab, the pinch bottom closure is opened in an area surrounding the tab.
In commonly-assigned U.S. patent application Ser. No. 08/768,389, the disclosure of which is hereby expressly incorporated herein by reference, an easy opening feature for industrial bags is also described. A tab is bonded into the bag with a portion extending outwardly from the bag, and the side walls of the bag are formed to include at least one tear line to cause localized tearing of the bag during opening as well as to reduce the effort required to open the bag. In particular embodiments of the bag, tear lines may be formed in both the front and back walls of the bag and arranged so as to align and overlap in a double fold closure.
Disposing the tab within the bag may cause difficulty when the bag is used for particular contents materials. For example, if the bag is to contain pet food, the pet food will typically have a desired fat content. Unless the tab is specially treated, such as coated with silicon or formed from synthetic materials, over time the tab will wick fatty oils from the pet food to the exterior of the bag. The fatty oils make the tab difficult to grasp hindering opening of the bag, may weaken the tab causing it to fail as the bag is opened, may distort printing disposed on the bag and/or the tab, and may further attract insects and rodents. Using silicon coated tabs and or synthetic materials to form the tab presents problems in effectively gluing the bag closed.
The present invention provides an easy open feature for an industrial bag utilizing a tab disposed on the exterior of the bag in combination with a uniquely glued closure.
In accordance with a preferred embodiment of the present invention, a bag includes a front wall, a back wall, first and second side walls interconnecting the front wall and the back wall, and an enclosed end defining an interior portion aid an exterior portion of the bag. The enclosed end includes a flap formed integral with the back wall that is folded over and bonded to the front wall using adhesive. A tab is secured to the front wall on the exterior of the bag and is disposed between the flap and the front wall. The tab is detachably secured to the front wall and the adhesive is disposed between the front wall and the flap in a pattern defining an adhesive void adjacent an opening edge of the bag.
The bag may also include a tab having a first portion disposed between the second flap and the front wall and a second portion extending along the front wall.
In alternate preferred embodiments, the tab may extend outwardly from beneath the flap, or may end at the edge of the flap.
The tab may also have a multi-ply construction including a first ply and a second ply. The first ply is substantially permanently bonded to the front wall on the exterior of the bag and the second ply is unsecured to the front wall.
The tab may also include a body portion and a tab portion. The body portion is bonded to the front wall and the tab portion extends over an opening edge of the front wall.
The tab may also include apertures through which the flap is bonded to the front wall.
The tab may be secured to the front wall using a peel-free adhesive.
In another aspect of the present invention, a bag includes a front wall, a back wall and first and second side walls interconnecting the front wall and the back wall. Each of the front wall, the back wall and the first and second side walls have a multiply construction, and the front wall and the first and second side walls each having an end edge. The end edges are preferably cut substantially flush, and the back wall has a flap extending from the back wall and beyond the end edges. A tab member is releasably secured to the front wall on an exterior portion of the bag and extends from the end edge along the front wall. An adhesive is disposed on the flap in a substantially continuous pattern, however, leaving a void area adjacent an opening edge of the bag.